How to send interrupt from Arduino and receive to C#

I want to use the Arduino (Lattepanda Leonardo) internal timer to generate an interrupt for every 20 milliseconds and accordingly want to receive this interrupt as a message in C# WPF. Using TimerOne.h and Firmata.h header files, I can able to create an interrupt for every 20 milliseconds and send a message "InterruptOccurred" (using Firmata.sendString("InterruptOccurred"); ) from Arduino. But using Lattepanda.Firmata package in WPF, C# I cannot able to receive the interrupt message in WPF. The code for Arduino and C# is attached herewith. Eagerly waiting for your valuable suggestions.

//Arduino code
#include <Firmata.h>
#include <TimerOne.h>

const long interval = 20; // Time interval in milliseconds
const int numberOfInterrupts = 20; // Number of interrupts to execute
volatile int interruptCounter = 0;

void setup() {
  Firmata.setFirmwareVersion(FIRMATA_FIRMWARE_MAJOR_VERSION, FIRMATA_FIRMWARE_MINOR_VERSION);
  Firmata.begin(57600);
  Timer1.initialize(interval * 1000); // Timer interval is in microseconds
  Timer1.attachInterrupt(timerISR); // Attach the ISR function

}

void loop() {
  if (interruptCounter >= numberOfInterrupts) {
    Timer1.stop();
    Firmata.sendString("Timer stopped");
    while (1) {} // Enter an infinite loop (halt the program)
  }
}

void timerISR() {
  // This function will be called every 20 milliseconds
  Firmata.sendString("CustomEvent");
  interruptCounter++;
}

// C# code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Threading;
using LattePanda.Firmata;
using System.IO.Ports;

namespace ArdIntrup
{

    public partial class MainWindow : Window
    {
        private SerialPort serialPort;

        public MainWindow()
        {
            InitializeComponent();
        }

        private void ConnectToArduino_Click(object sender, RoutedEventArgs e)
        {
            serialPort = new SerialPort("COM3", 57600);
            serialPort.DataReceived += SerialPort_DataReceived;

            try
            {
                serialPort.Open();
                MessageBox.Show("Connected to Arduino");
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error connecting to Arduino: " + ex.Message);
            }
        }
      
        private void SerialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
        {
            string receivedData = serialPort.ReadLine();
            Dispatcher.Invoke(() => {
                // Update the TextBox with the received message
                MessageTextBox.Text += receivedData + Environment.NewLine;
            });
        }

        private void InitializeSerialPort()
        {
            serialPort = new SerialPort("COM3", 57600);
            serialPort.DataReceived += SerialPort_DataReceived;
            serialPort.Open();
        }

        // Close the serial port when closing the application
        private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
        {
            if (serialPort != null && serialPort.IsOpen)
            {
                serialPort.Close();
            }
        }

    }
}