diff --git a/Cargo.lock b/Cargo.lock
index 0a56d80..49a6119 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -21,6 +21,7 @@ checksum = "c08606f8c3cbf4ce6ec8e28fb0014a2c086708fe954eaa885384a6165172e7e8"
 name = "bioz-icd-rs"
 version = "0.1.0"
 dependencies = [
+ "heapless 0.9.1",
  "postcard-rpc",
  "postcard-schema",
  "serde",
@@ -89,6 +90,17 @@ dependencies = [
  "stable_deref_trait",
 ]
 
+[[package]]
+name = "heapless"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b1edcd5a338e64688fbdcb7531a846cfd3476a54784dcb918a0844682bc7ada5"
+dependencies = [
+ "hash32 0.3.1",
+ "serde",
+ "stable_deref_trait",
+]
+
 [[package]]
 name = "lock_api"
 version = "0.4.13"
@@ -129,9 +141,9 @@ dependencies = [
 
 [[package]]
 name = "postcard-rpc"
-version = "0.11.13"
+version = "0.11.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e1af23d87c9a8308bbfaae655ac770ec10517e6448fa5e0b50838a36e5d860b9"
+checksum = "c7e1944dfb9859e440511700c442edce3eacd5862f90f5a9997d004bd3553f3b"
 dependencies = [
  "heapless 0.8.0",
  "portable-atomic",
@@ -143,10 +155,11 @@ dependencies = [
 
 [[package]]
 name = "postcard-schema"
-version = "0.2.4"
+version = "0.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f5a13d8b1f8b3473b45c2c779b97c18c260ac6458eb045d4be75df8087784400"
+checksum = "9475666d89f42231a0a57da32d5f6ca7f9b5cd4c335ea1fe8f3278215b7a21ff"
 dependencies = [
+ "heapless 0.9.1",
  "postcard-derive",
  "serde",
 ]
@@ -192,18 +205,28 @@ checksum = "56e6fa9c48d24d85fb3de5ad847117517440f6beceb7798af16b4a87d616b8d0"
 
 [[package]]
 name = "serde"
-version = "1.0.219"
+version = "1.0.228"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5f0e2c6ed6606019b4e29e69dbaba95b11854410e5347d525002456dbbb786b6"
+checksum = "9a8e94ea7f378bd32cbbd37198a4a91436180c5bb472411e48b5ec2e2124ae9e"
+dependencies = [
+ "serde_core",
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_core"
+version = "1.0.228"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41d385c7d4ca58e59fc732af25c3983b67ac852c1a25000afe1175de458b67ad"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.219"
+version = "1.0.228"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b0276cf7f2c73365f7157c8123c21cd9a50fbbd844757af28ca1f5925fc2a00"
+checksum = "d540f220d3187173da220f885ab66608367b6574e925011a9353e4badda91d79"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/Cargo.toml b/Cargo.toml
index 8602951..84b97b4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -5,10 +5,10 @@ edition = "2024"
 
 [dependencies]
 postcard-rpc = { version = "0.11.15" }
-heapless = { version = "0.9.0", features = ["serde"] }
+heapless = { version = "0.9.1", features = ["serde"] }
 
 [dependencies.serde]
-version = "1.0.219"
+version = "1.0.228"
 features = ["derive"]
 default-features = false
 
diff --git a/src/lib.rs b/src/lib.rs
index 4b5e0d4..901ecab 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -75,6 +75,12 @@ pub struct MultiImpedanceResult {
     pub periods_per_dft_18: Vec<f32, 18>,
 }
 
+#[derive(Clone, Copy, Serialize, Deserialize, Schema, Debug, PartialEq)]
+pub enum BioImpedanceLeadMode {
+    TwoLead,
+    FourLead,
+}
+
 #[derive(Clone, Copy, Serialize, Deserialize, Schema, Debug, PartialEq)]
 pub enum IcdDftNum {
     Num4,
@@ -96,6 +102,7 @@ pub enum IcdDftNum {
 pub struct SingleImpedanceStartRequest {
     pub update_frequency: u32,
     pub sinus_frequency: u32,
+    pub lead_mode: BioImpedanceLeadMode,
     pub dft_number: IcdDftNum,
 }